Coverage enhancements for physical broadcast channel (PBCH)

ABSTRACT

Certain aspects of the present disclosure generally relate to wireless communications, and more specifically, coverage enhancements for physical broadcast channel (PBCH). According to certain aspects, a method is provided for wireless communications by a user equipment (UE). The method generally includes receiving a physical downlink shared channel (PDSCH) transmission, receiving a different type downlink transmission, with transmit power boosted relative to the PDSCH transmission, receiving information regarding relative transmit power of the PDSCH transmission relative to a common reference signal (CRS) based on the transmit power of the different type downlink transmission, and processing the PDSCH transmission based on the information.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims benefit of U.S. Provisional Patent ApplicationSer. No. 61/879,634, filed Sep. 18, 2013, which is herein incorporatedby reference in its entirety.

BACKGROUND

I. Field of the Invention

Certain aspects of the present disclosure generally relate to wirelesscommunications, and more specifically, to coverage enhancements forphysical broadcast channel (PBCH).

II. Description of Related Art

Wireless communication systems are widely deployed to provide varioustypes of communication content such as voice, data, and so on. Thesesystems may be multiple-access systems capable of supportingcommunication with multiple users by sharing the available systemresources (e.g., bandwidth and transmit power). Examples of suchmultiple-access systems include code division multiple access (CDMA)systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, 3rd Generation PartnershipProject (3GPP) Long Term Evolution (LTE) including LTE-Advanced systemsand orthogonal frequency division multiple access (OFDMA) systems.

Generally, a wireless multiple-access communication system cansimultaneously support communication for multiple wireless terminals.Each terminal communicates with one or more base stations viatransmissions on the forward and reverse links. The forward link (ordownlink) refers to the communication link from the base stations to theterminals, and the reverse link (or uplink) refers to the communicationlink from the terminals to the base stations. This communication linkmay be established via a single-input single-output, multiple-inputsingle-output or a multiple-input multiple-output (MIMO) system.

SUMMARY

The systems, methods, and devices of the disclosure each have severalaspects, no single one of which is solely responsible for its desirableattributes. Without limiting the scope of this disclosure as expressedby the claims which follow, some features will now be discussed briefly.After considering this discussion, and particularly after reading thesection entitled “Detailed Description” one will understand how thefeatures of this disclosure provide advantages that include improvedcommunications between access points and stations in a wireless network.

Techniques and apparatus are provided herein for coverage enhancementsfor physical broadcast channel (PBCH).

Certain aspects of the present disclosure provide a method for wirelesscommunications by a base station (BS). The method generally includesobtaining a first set of one or more power allocation parameters for usein transmitting a physical downlink share channel (PDSCH) andtransmitting a different type downlink transmission, with transmit powerboosted relative to a PDSCH transmission sent using the first set ofpower allocation parameters, based on a second set of one or more powerallocation parameters. Certain aspects of the present disclosure providean apparatus for wireless communications by a base station (BS). Theapparatus generally includes at least one controller or processorconfigured to: obtain a first set of one or more power allocationparameters for use in transmitting a physical downlink share channel(PDSCH) and transmit a different type downlink transmission, withtransmit power boosted relative to a PDSCH transmission sent using thefirst set of power allocation parameters, based on a second set of oneor more power allocation parameters

Certain aspects of the present disclosure provide a method for wirelesscommunications by a user equipment (UE). The method generally includesreceiving a PDSCH transmission, receiving a different type downlinktransmission, with transmit power boosted relative to the PDSCHtransmission, receiving information regarding relative transmit power ofthe PDSCH transmission relative to a common reference signal (CRS) basedon the transmit power of the different type downlink transmission, andprocessing the PDSCH transmission based on the information. Certainaspects of the present disclosure provide an apparatus for wirelesscommunications by a user equipment (UE). The apparatus generallyincludes at least one controller or processor configured to: receive aPDSCH transmission, receive a different type downlink transmission, withtransmit power boosted relative to the PDSCH transmission, receiveinformation regarding relative transmit power of the PDSCH transmissionrelative to a common reference signal (CRS) based on the transmit powerof the different type downlink transmission, and process the PDSCHtransmission based on the information.

Certain aspects of the present disclosure provide a method for wirelesscommunications by a BS. The method generally includes transmitting aPBCH in at least one subframe of a radio frame and repeatingtransmission of the PBCH in at least one of: the same subframe or in adifferent subframe of the radio frame. Certain aspects of the presentdisclosure provide an apparatus for wireless communications by a BS. Theapparatus generally includes at least one controller or processorconfigured to: transmit a PBCH in at least one subframe of a radio frameand repeat transmission of the PBCH in at least one of: the samesubframe or in a different subframe of the radio frame.

Certain aspects of the present disclosure provide a method for wirelesscommunications by a UE. The method generally includes receiving ratematching information for a repeated PBCH transmission in a radio frameand processing downlink transmissions in the radio frame, based on therate matching information. Certain aspects of the present disclosureprovide an apparatus for wireless communications by a UE. The apparatusgenerally includes at least one controller or processor configured to:receive rate matching information for a repeated PBCH transmission in aradio frame and process downlink transmissions in the radio frame, basedon the rate matching information.

Certain aspects of the present disclosure provide a method for wirelesscommunications by a BS. The method generally includes receiving abundled random access channel (RACH) transmission from a UE andtriggering bundled transmission of broadcast information, in response toreceiving the bundled RACH transmission. Certain aspects of the presentdisclosure provide an apparatus for wireless communications by a BS. Theapparatus generally includes at least one controller or processorconfigured to: receive a bundled random access channel (RACH)transmission from a UE and trigger bundled transmission of broadcastinformation, in response to receiving the bundled RACH transmission.

Certain aspects of the present disclosure provide a method for wirelesscommunications by a UE. The method generally includes receiving abundled transmission of a system information block (SIB) that indicatesa bundled physical RACH (PRACH) configuration and performing a bundledRACH transmission in accordance with the PRACH configuration in order totrigger bundled transmission of broadcast information. Certain aspectsof the present disclosure provide an apparatus for wirelesscommunications by a UE. The apparatus generally includes at least onecontroller or processor configured to: receive a bundled transmission ofa system information block (SIB) that indicates a bundled physical RACH(PRACH) configuration and perform a bundled RACH transmission inaccordance with the PRACH configuration in order to trigger bundledtransmission of broadcast information.

Numerous other aspects are provided including methods, apparatus,systems, computer program products, and processing systems.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the presentdisclosure can be understood in detail, a more particular description,briefly summarized above, may be had by reference to aspects, some ofwhich are illustrated in the appended drawings. It is to be noted,however, that the appended drawings illustrate only certain typicalaspects of this disclosure and are therefore not to be consideredlimiting of its scope, for the description may admit to other equallyeffective aspects.

FIG. 1 is a block diagram conceptually illustrating an example wirelesscommunication network, in accordance with certain aspects of the presentdisclosure.

FIG. 2 is a block diagram conceptually illustrating an example of anevolved node B (eNB) in communication with a user equipment (UE) in awireless communications network, in accordance with certain aspects ofthe present disclosure.

FIG. 3 is a block diagram conceptually illustrating an example framestructure for a particular radio access technology (RAT) for use in awireless communications network, in accordance with certain aspects ofthe present disclosure.

FIG. 4 illustrates example subframe formats for the downlink with anormal cyclic prefix, in accordance with certain aspects of the presentdisclosure.

FIG. 5 illustrates example operations for a base station, in accordancewith certain aspects of the present disclosure.

FIG. 5A illustrates example means capable of performing the operationsshown in FIG. 5, in accordance with certain aspects of the presentdisclosure.

FIG. 6 illustrates example operations for a UE, in accordance withcertain aspects of the present disclosure.

FIG. 6A illustrates example means capable of performing the operationsshown in FIG. 6, in accordance with certain aspects of the presentdisclosure.

FIG. 7 illustrates example operations for a base station, in accordancewith certain aspects of the present disclosure.

FIG. 7A illustrates example means capable of performing the operationsshown in FIG. 7, in accordance with certain aspects of the presentdisclosure.

FIG. 8 illustrates example operations for a UE, in accordance withcertain aspects of the present disclosure.

FIG. 8A illustrates example means capable of performing the operationsshown in FIG. 8, in accordance with certain aspects of the presentdisclosure.

FIG. 9 illustrates example operations for a BS, in accordance withcertain aspects of the present disclosure.

FIG. 9A illustrates example means capable of performing the operationsshown in FIG. 9, in accordance with certain aspects of the presentdisclosure.

FIG. 10 illustrates example operations for a UE, in accordance withcertain aspects of the present disclosure.

FIG. 10A illustrates example means capable of performing the operationsshown in FIG. 10, in accordance with certain aspects of the presentdisclosure.

DETAILED DESCRIPTION

Aspects of the present disclosure provide techniques and apparatus forenhancing downlink coverage for certain user equipments (e.g., low cost,low data rate UEs).

The techniques described herein may be used for various wirelesscommunication networks such as Code Division Multiple Access (CDMA)networks, Time Division Multiple Access (TDMA) networks, FrequencyDivision Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA)networks, Single-Carrier FDMA (SC-FDMA) networks, etc. The terms“network” and “system” are often used interchangeably. A CDMA networkmay implement a radio technology such as Universal Terrestrial RadioAccess (UTRA), cdma2000, etc. UTRA includes Wideband-CDMA (W-CDMA), TimeDivision Synchronous CDMA (TD-SCDMA), and other variants of CDMA.cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network mayimplement a radio technology such as Global System for MobileCommunications (GSM). An OFDMA network may implement a radio technologysuch as Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11(Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDM®, etc. UTRA andE-UTRA are part of Universal Mobile Telecommunication System (UMTS).3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A), in bothfrequency division duplex (FDD) and time division duplex (TDD), are newreleases of UMTS that use E-UTRA, which employs OFDMA on the downlinkand SC-FDMA on the uplink. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM aredescribed in documents from an organization named “3rd GenerationPartnership Project” (3GPP). cdma2000 and UMB are described in documentsfrom an organization named “3rd Generation Partnership Project 2”(3GPP2). The techniques described herein may be used for the wirelessnetworks and radio technologies mentioned above as well as otherwireless networks and radio technologies. For clarity, certain aspectsof the techniques are described below for LTE/LTE-A, and LTE/LTE-Aterminology is used in much of the description below.

An Example Wireless Communications System

FIG. 1 shows a wireless communication network 100, which may be an LTEnetwork or some other wireless network in which the techniques andapparatus of the present disclosure may be applied. Wireless network 100may include a number of evolved Node Bs (eNBs) 110 and other networkentities. An eNB is an entity that communicates with user equipments(UEs) and may also be referred to as a base station, a Node B, an accesspoint (AP), etc. Each eNB may provide communication coverage for aparticular geographic area. In 3GPP, the term “cell” can refer to acoverage area of an eNB or an eNB subsystem serving this coverage area,depending on the context in which the term is used.

An eNB may provide communication coverage for a macro cell, a pico cell,a femto cell, or other types of cell. A macro cell may cover arelatively large geographic area (e.g., several kilometers in radius)and may allow unrestricted access by UEs with service subscription. Apico cell may cover a relatively small geographic area and may allowunrestricted access by UEs with service subscription. A femto cell maycover a relatively small geographic area (e.g., a home) and may allowrestricted access by UEs having association with the femto cell (e.g.,UEs in a closed subscriber group (CSG)). An eNB for a macro cell may bereferred to as a macro eNB. An eNB for a pico cell may be referred to asa pico eNB. An eNB for a femto cell may be referred to as a femto eNB ora home eNB (HeNB). In the example shown in FIG. 1, an eNB 110 a may be amacro eNB for a macro cell 102 a, an eNB 110 b may be a pico eNB for apico cell 102 b, and an eNB 110 c may be a femto eNB for a femto cell102 c. An eNB may support one or multiple (e.g., three) cells. The terms“eNB”, “base station,” and “cell” may be used interchangeably herein.

Wireless network 100 may also include relay stations. A relay station isan entity that can receive a transmission of data from an upstreamstation (e.g., an eNB or a UE) and send a transmission of the data to adownstream station (e.g., a UE or an eNB). A relay station may also be aUE that can relay transmissions for other UEs. In the example shown inFIG. 1, a relay station 110 d may communicate with macro eNB 110 a and aUE 120 d in order to facilitate communication between eNB 110 a and UE120 d. A relay station may also be referred to as a relay eNB, a relaybase station, a relay, etc.

Wireless network 100 may be a heterogeneous network that includes eNBsof different types, e.g., macro eNBs, pico eNBs, femto eNBs, relay eNBs,etc. These different types of eNBs may have different transmit powerlevels, different coverage areas, and different impact on interferencein wireless network 100. For example, macro eNBs may have a hightransmit power level (e.g., 5 to 40 W) whereas pico eNBs, femto eNBs,and relay eNBs may have lower transmit power levels (e.g., 0.1 to 2 W).

A network controller 130 may couple to a set of eNBs and may providecoordination and control for these eNBs. Network controller 130 maycommunicate with the eNBs via a backhaul. The eNBs may also communicatewith one another, e.g., directly or indirectly via a wireless orwireline backhaul.

UEs 120 (e.g., 120 a, 120 b, 120 c) may be dispersed throughout wirelessnetwork 100, and each UE may be stationary or mobile. A UE may also bereferred to as an access terminal, a terminal, a mobile station (MS), asubscriber unit, a station (STA), etc. A UE may be a cellular phone, apersonal digital assistant (PDA), a wireless modem, a wirelesscommunication device, a handheld device, a laptop computer, a cordlessphone, a wireless local loop (WLL) station, a tablet, a smart phone, anetbook, a smartbook, an ultrabook, etc.

FIG. 2 is a block diagram of a design of base station/eNB 110 and UE120, which may be one of the base stations/eNBs and one of the UEs inFIG. 1. Base station 110 may be equipped with T antennas 234 a through234 t, and UE 120 may be equipped with R antennas 252 a through 252 r,where in general T≥1 and R≥1.

At base station 110, a transmit processor 220 may receive data from adata source 212 for one or more UEs, select one or more modulation andcoding schemes (MCSs) for each UE based on channel quality indicators(CQIs) received from the UE, process (e.g., encode and modulate) thedata for each UE based on the MCS(s) selected for the UE, and providedata symbols for all UEs. Transmit processor 220 may also process systeminformation (e.g., for semi-static resource partitioning information(SRPI), etc.) and control information (e.g., CQI requests, grants, upperlayer signaling, etc.) and provide overhead symbols and control symbols.Processor 220 may also generate reference symbols for reference signals(e.g., the common reference signal (CRS)) and synchronization signals(e.g., the primary synchronization signal (PSS) and secondarysynchronization signal (SSS)). A transmit (TX) multiple-inputmultiple-output (MIMO) processor 230 may perform spatial processing(e.g., precoding) on the data symbols, the control symbols, the overheadsymbols, or the reference symbols, if applicable, and may provide Toutput symbol streams to T modulators (MODs) 232 a through 232 t. Eachmodulator 232 may process a respective output symbol stream (e.g., forOFDM, etc.) to obtain an output sample stream. Each modulator 232 mayfurther process (e.g., convert to analog, amplify, filter, andupconvert) the output sample stream to obtain a downlink signal. Tdownlink signals from modulators 232 a through 232 t may be transmittedvia T antennas 234 a through 234 t, respectively.

At UE 120, antennas 252 a through 252 r may receive the downlink signalsfrom base station 110 or other base stations and may provide receivedsignals to demodulators (DEMODs) 254 a through 254 r, respectively. Eachdemodulator 254 may condition (e.g., filter, amplify, downconvert, anddigitize) its received signal to obtain input samples. Each demodulator254 may further process the input samples (e.g., for OFDM, etc.) toobtain received symbols. A MIMO detector 256 may obtain received symbolsfrom all R demodulators 254 a through 254 r, perform MIMO detection onthe received symbols if applicable, and provide detected symbols. Areceive processor 258 may process (e.g., demodulate and decode) thedetected symbols, provide decoded data for UE 120 to a data sink 260,and provide decoded control information and system information to acontroller/processor 280. A channel processor may determine referencesignal received power (RSRP), received signal strength indicator (RSSI),reference signal received quality (RSRQ), CQI, etc.

On the uplink, at UE 120, a transmit processor 264 may receive andprocess data from a data source 262 and control information (e.g., forreports comprising RSRP, RSSI, RSRQ, CQI, etc.) fromcontroller/processor 280. Processor 264 may also generate referencesymbols for one or more reference signals. The symbols from transmitprocessor 264 may be precoded by a TX MIMO processor 266 if applicable,further processed by modulators 254 a through 254 r (e.g., for SC-FDM,OFDM, etc.), and transmitted to base station 110. At base station 110,the uplink signals from UE 120 and other UEs may be received by antennas234, processed by demodulators 232, detected by a MIMO detector 236 ifapplicable, and further processed by a receive processor 238 to obtaindecoded data and control information sent by UE 120. Processor 238 mayprovide the decoded data to a data sink 239 and the decoded controlinformation to controller/processor 240. Base station 110 may includecommunication unit 244 and communicate to network controller 130 viacommunication unit 244. Network controller 130 may include communicationunit 294, controller/processor 290, and memory 292.

Controllers/processors 240 and 280 may direct the operation at basestation 110 and UE 120, respectively. Controller/processor 240 or othercontrollers/processors and modules at base station 110, orcontroller/processor 280 or other controllers/processors and modules atUE 120, may perform or direct processes for the techniques describedherein. Memories 242 and 282 may store data and program codes for basestation 110 and UE 120, respectively. A scheduler 246 may schedule UEsfor data transmission on the downlink or uplink.

When transmitting data to the UE 120, the base station 110 may beconfigured to determine a bundling size based at least in part on a dataallocation size and precode data in bundled contiguous resource blocksof the determined bundling size, wherein resource blocks in each bundlemay be precoded with a common precoding matrix. That is, referencesignals (RSs) such as UE-RS or data in the resource blocks may beprecoded using the same precoder. The power level used for the UE-RS ineach resource block (RB) of the bundled RBs may also be the same.

The UE 120 may be configured to perform complementary processing todecode data transmitted from the base station 110. For example, the UE120 may be configured to determine a bundling size based on a dataallocation size of received data transmitted from a base station inbundles of contiguous RBs, wherein at least one reference signal inresource blocks in each bundle are precoded with a common precodingmatrix, estimate at least one precoded channel based on the determinedbundling size and one or more RSs transmitted from the base station, anddecode the received bundles using the estimated precoded channel.

FIG. 3 shows an exemplary frame structure 300 for FDD in LTE. Thetransmission timeline for each of the downlink and uplink may bepartitioned into units of radio frames. Each radio frame may have apredetermined duration (e.g., 10 milliseconds (ms)) and may bepartitioned into 10 subframes with indices of 0 through 9. Each subframemay include two slots. Each radio frame may thus include 20 slots withindices of 0 through 19. Each slot may include L symbol periods, e.g.,seven symbol periods for a normal cyclic prefix (as shown in FIG. 2) orsix symbol periods for an extended cyclic prefix. The 2L symbol periodsin each subframe may be assigned indices of 0 through 2L-1.

In LTE, an eNB may transmit a primary synchronization signal (PSS) and asecondary synchronization signal (SSS) on the downlink in the center1.08 MHz of the system bandwidth for each cell supported by the eNB. ThePSS and SSS may be transmitted in symbol periods 6 and 5, respectively,in subframes 0 and 5 of each radio frame with the normal cyclic prefix,as shown in FIG. 3. The PSS and SSS may be used by UEs for cell searchand acquisition. The eNB may transmit a cell-specific reference signal(CRS) across the system bandwidth for each cell supported by the eNB.The CRS may be transmitted in certain symbol periods of each subframeand may be used by the UEs to perform channel estimation, channelquality measurement, or other functions. The eNB may also transmit aphysical broadcast channel (PBCH) in symbol periods 0 to 3 in slot 1 ofcertain radio frames. The PBCH may carry some system information. TheeNB may transmit other system information such as system informationblocks (SIBs) on a physical downlink shared channel (PDSCH) in certainsubframes. The eNB may transmit control information/data on a physicaldownlink control channel (PDCCH) in the first B symbol periods of asubframe, where B may be configurable for each subframe. The eNB maytransmit traffic data or other data on the PDSCH in the remaining symbolperiods of each subframe.

The PSS, SSS, CRS, and PBCH in LTE are described in 3GPP TS 36.211,entitled “Evolved Universal Terrestrial Radio Access (E-UTRA); PhysicalChannels and Modulation,” which is publicly available.

FIG. 4 shows two example subframe formats 410 and 420 for the downlinkwith a normal cyclic prefix. The available time frequency resources forthe downlink may be partitioned into resource blocks. Each resourceblock may cover 12 subcarriers in one slot and may include a number ofresource elements. Each resource element may cover one subcarrier in onesymbol period and may be used to send one modulation symbol, which maybe a real or complex value.

Subframe format 410 may be used for an eNB equipped with two antennas. ACRS may be transmitted from antennas 0 and 1 in symbol periods 0, 4, 7,and 11. A reference signal is a signal that is known a priori by atransmitter and a receiver and may also be referred to as pilot. A CRSis a reference signal that is specific for a cell, e.g., generated basedon a cell identity (ID). In FIG. 4, for a given resource element withlabel Ra, a modulation symbol may be transmitted on that resourceelement from antenna a, and no modulation symbols may be transmitted onthat resource element from other antennas. Subframe format 420 may beused for an eNB equipped with four antennas. A CRS may be transmittedfrom antennas 0 and 1 in symbol periods 0, 4, 7, and 11 and fromantennas 2 and 3 in symbol periods 1 and 8. For both subframe formats410 and 420, a CRS may be transmitted on evenly spaced subcarriers,which may be determined based on cell ID. Different eNBs may transmittheir CRSs on the same or different subcarriers, depending on their cellIDs. For both subframe formats 410 and 420, resource elements not usedfor the CRS may be used to transmit data (e.g., traffic data, controldata, or other data).

An interlace structure may be used for each of the downlink and uplinkfor FDD in LTE. For example, Q interlaces with indices of 0 through Q-1may be defined, where Q may be equal to 4, 6, 8, 10, or some othervalue. Each interlace may include subframes that are spaced apart by Qframes. In particular, interlace q may include subframes q, q+Q, q+2Q,etc., where q∈{0, . . . , Q-1}.

The wireless network may support hybrid automatic retransmission request(HARQ) for data transmission on the downlink and uplink. For HARQ, atransmitter (e.g., an eNB 110) may send one or more transmissions of apacket until the packet is decoded correctly by a receiver (e.g., a UE120) or some other termination condition is encountered. For synchronousHARQ, all transmissions of the packet may be sent in subframes of asingle interlace. For asynchronous HARQ, each transmission of the packetmay be sent in any subframe.

A UE may be located within the coverage of multiple eNBs. One of theseeNBs may be selected to serve the UE. The serving eNB may be selectedbased on various criteria such as received signal strength, receivedsignal quality, path loss, etc. Received signal quality may bequantified by a signal-to-interference-plus-noise ratio (SINR), or areference signal received quality (RSRQ), or some other metric. The UEmay operate in a dominant interference scenario in which the UE mayobserve high interference from one or more interfering eNBs.

Example PBCH Design with Coverage Enhancements

In certain systems (e.g., Long Term Evolution (LTE) Release 8 or morerecent), transmission time interval (TTI) bundling (e.g., subframebundling) can be configured on a per-user equipment (UE) basis. TTIbundling may be configured by the parameter, ttiBundling, provided fromhigher layers. If TTI bundling is configured for a UE, the subframebundling operation may only be applied to the uplink shared channel(UL-SCH), for example, physical uplink shared channel (PUSCH), and maynot be applied to other uplink signals or traffic (e.g., such as uplinkcontrol information (UCI)). In some cases, TTI bundling size is fixed atfour subframes (e.g., the PUSCH is transmitted in four consecutivesubframes). The same hybrid automatic repeat request (HARQ) processnumber can be used in each of the bundled subframes. The resourceallocation size may be restricted to up to three resource blocks (RBs)and the modulation order can be set to two (e.g., quadrature phase shiftkeying (QPSK)). A TTI bundle can be treated as a single resource forwhich a single grant and a single HARQ acknowledgement (ACK) is used foreach bundle.

For certain systems (e.g., LTE Release 12), coverage enhancements (e.g.,for physical broadcast channel (PBCH)) may be desirable in a variety ofscenarios. For example, coverage enhancements may be desirable forproviding service to machine-type communication (MTC) devices or devicesin deep coverage holes (e.g., in basements, or valleys). Coverageenhancements may be desirable in deployment of higher frequencies (e.g.,high microwave or millimeter wave frequencies) for increased bandwidthcommunications. Coverage enhancements may further be desired for lowdata rate users, delay tolerant users, voice over internet protocol(VoIP) and medium data rate users, and so on.

Typically, PBCH is transmitted every 40 ms with one burst every 10 ms.According to certain aspects, for PBCH coverage enhancement, an eNodeB(eNB) may perform repetition or bundling of the PBCH. According tocertain aspects, for PBCH coverage enhancement, an eNB may boosttransmission power for transmissions to the UE. According to certainaspects, for PBCH coverage enhancement, an eNB may reduce the payloadsize of PBCH.

Power Boosting for PBCH

As mentioned above, according to certain aspects, PBCH may be powerboosted (transmitted with increased power) in order to enhance coverage.Increases in power can be generated in a variety of ways. For example,the eNB may reallocate some null tones and use the power that would havebeen used to transmit on null tones for increasing PBCH transmissionpower. In another example, power spectral density (PSD) may be reducedacross one or more tones from other frequency locations, and the powerreductions from each power reduced tone may be allocated to increasePBCH transmission power.

According to certain aspects, the eNB may signal the power boost to theUE. Two power allocation parameters on the physical downlink sharedchannel (PDSCH) may be notated as Pa and Pb. A range for Pa may be {−6,−4.77, −3, −1.77, 0, 1, 2, 3} dB and a range for Pb may be {0, 1, 2, 3}.Pa and Pb can be controlled by radio resource control (RRC) signaling(e.g., in information elements) and a UE may calculate PDSCH power basedon Pa and Pb.

According to certain aspects, for an eNB that transmits on a widebandwidth, the eNB may boost the power of a PBCH and reduce theremaining power on the other PDSCH tones in the four PBCH transmissionsymbols. For example, the eNB may signal the power adjustment on each ofthe four symbols where PBCH is transmitted for PDSCH transmissions inthe other frequency tones. Alternatively, the eNB may transmit some nulltones in these four symbols, where PBCH is transmitted, and may alsosignal the UE to rate match around the null tones.

When PBCH is power boosted, one may introduce new Pa′ and Pb′ parametersto signal the amount of power that has been reallocated to the PBCHsimilar to currently defined Pa and Pb for symbols with and without CRS.According to certain aspects, power boosting may also apply to secondarysynchronization signal (SSS) and primary synchronization signal (PSS),the eNB may signal power adjustment to the UE using transmit powerallocation parameters Pa″ and Pb″, which may also be similar to Pa andPb, respectively. In cases where PSS or SSS is power boosted, powerscaling parameter Pb″ may be introduced to signal that PSS or SSS ispower boosted. In some cases, some subsets of Pa′, Pa″, Pb′, Pb″ may bethe same, and same or different parameters may be reused for null tones.In aspects, where PSS or SSS is power boosted, parameter Pa′ may beomitted, as PSS and SSS do not contain a common reference signal (CRS).

PBCH Time-Domain Repetition

As mentioned above, PBCH may be repeated in order to enhance coverage.According to certain aspects, PBCH may be repeated in the time domain(e.g., bundled). For example, PBCH may be transmitted in multiplesubframes within a radio frame. For example, where the transmissionbandwidth is greater than 1.4 MHz, PBCH may be transmitted in subframe 0(the typical position for PBCH transmission as shown in FIG. 3) andrepeated in subframe 5. Thus, PBCH may achieve twice the coverage.According to certain aspects, system information block 1 (SIB1) may betransmitted outside of the center six resource blocks (RBs). However, ifthe bandwidth is 1.4 MHz, then PBCH can be repeated in subframe 0 in allradio frames, and subframe 5 only in odd radio frames, as subframe 5 foreven radio frames is used for SIB1 transmission.

In another example, PBCH may be transmitted in subframe 0 and repeatedin another subframe. For example, PBCH may be repeated in subframe 1 or9 to be adjacent to the PBCH transmitted in subframe 0. PBCH may betransmitted in subframe 4 or 6 to be adjacent to the PBCH transmitted insubframe 5. Transmitting PBCH in a frame or multiple frames adjacent tosubframe 0, subframe 5, or both subframes 0 and 5 may reduce UE wake uptime or measurement gaps, as the UE performs PSS/SSS detection insubframes 0 and 5.

According to certain aspects, PBCH may be repeated within the samesubframe. For example, since PBCH is transmitted on 4 symbols, twocopies of PBCH may be sent if a subframe has at least four surplussymbols

According to certain aspects, PBCH may be repeated in differentsubframes within a radio frame and may also be repeated multiple timeswithin a subframe.

PBCH Frequency-Domain Repetition

According to certain aspects, PBCH may be repeated in the frequencydomain to achieve enhanced coverage. Typically PBCH is transmitted inthe center 6 RBs of four consecutive OFDM symbols in subframe 0 of eachradio frame (e.g., as shown in FIG. 3). Frequency domain repetition canbe performed where a system is operating on a wide bandwidth (e.g., morethan 6 RBs) allowing PBCH to be repeated at different frequencies.According to certain aspects, PBCH may be transmitted (repeated) at theedge of the band to achieve maximum diversity.

According to certain aspects, before decoding PBCH, the UE may not knowthe bandwidth. According to certain aspects, PBCH may always be repeatedat the same frequency location. For example, the PBCH may always berepeated on a fixed location (e.g., at the edge of 5 MHz regardless ofactual transmission bandwidth). According to certain aspects, PBCH mayalways be repeated at the band edge of the downlink bandwidth and thereceiving UE may perform blind decoding of the PBCH to determine theactual bandwidth.

According to certain aspects, PBCH may be repeated in both the timedomain and the frequency domain (e.g., 2D repetition).

According to certain aspects, for enhanced coverage for PBCH, whether bypower boosting, time-domain repetition, or frequency-domain repetition,may involve transmission of the enhanced PBCH in all radio frames suchthat the coverage enhancement is always available. Alternatively, PBCHcoverage enhancements may be transmitted only in some radio frames wheresuch coverage enhancement is necessary or desired.

Rate Matching

According to certain aspects, the eNB may inform the UE of PBCH coverageenhancements to allow PDSCH rate matching around the enhanced PBCH. ForPBCH with enhanced coverage by time-domain repetition of the PBCH, theeNB may inform the UE of the repetition pattern of PBCH within subframesor across subframes. For PBCH with power boosting with null tones, theeNB may inform the UE of the power boost level and the allocation ofnull tones. According to certain aspects, the remaining tones may beassigned for PDSCH. Rate matching may be performed around the entire RBwhere the enhanced PBCH is allocated. Alternatively, rate matching maybe performed around the enhanced PBCH resource element (RE).

According to certain aspects, the various signaling options may be usedfor the eNB to signal to the UE that the eNB is operating in PBCHenhanced coverage mode. For example, the eNB may broadcast SIB with thePBCH rate matching information. Alternatively, the eNB may use RRCsignaling of the PBCH rate matching information. In yet anotheralternative, the eNB may reuse quasi-collocation and the PDSCH ratematching signaling mechanism to signal the PBCH rate matchinginformation. According to certain aspects, where PSS or SSS is powerboosted, similar rate matching operations and signaling may be usedaround null tones.

According to certain aspects, the eNB may perform bundled broadcasttransmissions opportunistically for PBCH with coverage enhancements. Forexample, the UE may signal the eNB that PBCH coverage enhancements aredesired by transmitting a bundled random access channel (RACH)transmission to the eNB. According to certain aspects, the bundledbroadcast transmissions from the eNB may include only a subset of SIBs(e.g., SIB2 and above), all the SIBs, or both the PBCH and SIBs.According to certain aspects, where the bundled broadcast includes asubset of SIBs, PBCH and SIB1 may always be bundled, and the eNB mayactivate SIB subset bundling on receipt of the bundled RACH from the UE,the UE may obtain the configuration of bundled RACH from SIB1. Accordingto certain aspects, after the eNB sends the UE the bundled broadcasttransmission, the eNB may turn off bundling for serving other UEs (e.g.,for SIB2 and above).

According to certain aspects, the bundled broadcast transmissionincludes all SIBs, a simplified bundled SIB may be used to indicate abundled PRACH configuration. According to certain aspects, afterdetection of a bundled RACH, the eNB may commence broadcasting bundledSIBs. According to certain aspects, the UE may send a preconfigured RACHwith at least a predefined RACH sequence, starting position relative toPSS/SSS, and other parameters as appropriate.

FIG. 5 illustrates example operations 500 for wireless communications,in accordance with certain aspects of the present disclosure. Theoperations may be performed, for example, by a base station (e.g., eNB110). The operations 500 may begin, at 502, by obtaining a first set ofone or more power allocation parameters for use in transmitting aphysical downlink shared channel (PDSCH).

At 504, the base station may transmit a different type downlinktransmission (e.g., a PBCH, PSS, SSS), with transmit power boostedrelative to a PDSCH transmission (e.g., sent using the first set ofpower allocation parameters), based on a second set of one or more powerallocation parameters. According to certain aspects, the BS may transmitPDSCH with power adjusted to compensate for transmitting the differenttype downlink transmission with boosted transmit power. According tocertain aspects, the base station may signal information regarding thesecond set of power allocation parameters to a UE. For example, thesecond set of one or more power allocation parameters may include atleast one power allocation parameter for PBCH symbols and at least onepower allocation parameter for non-PBCH symbols. Transmitting thedifferent type downlink transmission may include boosting power of PBCHsymbols while transmitting null tones on some frequency tones.

According to certain aspects, the base station may signal rate matchinginformation for the PBCH transmission with null tones via at least oneof a SIB, RRC signaling, new PBCH rate matching information, or reuse ofquasi-collocation signaling. Transmitting the PBCH may include boostingpower of PBCH symbols while reducing transmission power on remainingPDSCH symbols.

In aspects, the BS may also signal information regarding a poweradjustment for the remaining PDSCH symbols.

FIG. 6 illustrates example operations 600 for wireless communications,in accordance with certain aspects of the present disclosure. Theoperations 600 may be performed, for example, by a UE (e.g., UE 120).The operations 600 may begin, at 602, by receiving a PDSCH transmission.

At 604, the UE may receive a different type downlink transmission, withtransmit power boosted relative to the PDSCH transmission. For example,the UE may receive a PBCH with transmit power boosted based on a secondset of one or more power allocation parameters (e.g., at least one powerallocation parameter for PBCH symbols and at least one power allocationparameter for non-PBCH symbols). In another example, the UE may receiveat least one synchronization signal.

At 606, the UE may receive information regarding relative transmit powerof the PDSCH transmission relative to a common reference signal (CRS)based on the transmit power of the different type downlink transmission.For example, the UE may receive signaling regarding a power adjustmentfor null tones. In another example, the UE may receive signalingregarding a power adjustment for PDSCH symbols not used for PBCH.

According to certain aspects, the UE may also receive rate matchinginformation for the PBCH transmission via at least one of a SIB, RRCsignaling, new PBCH rate matching information, or reuse ofquasi-collocation signaling.

At 608, the UE may process the PDSCH transmission based on theinformation received at 606.

FIG. 7 illustrates example operations 700 for wireless communications,in accordance with certain aspects of the present disclosure. Theoperations may be performed, for example, by a base station (e.g., eNB110). The operations 700 may begin, at 702, by transmitting a PBCH in atleast one subframe of a radio frame.

At 704, the base station repeats transmission of the PBCH in at leastone of: the same subframe (e.g., using different symbols or differentfrequency than the first PBCH) or in a different subframe of the radioframe. According to certain aspects, the PBCH transmission may berepeated only with certain operating bandwidths. According to certainaspects, the PBCH transmission may be repeated with a same version andpayload in each transmission. According to certain aspects, the PBCHtransmission may be repeated only in certain radio frames. According tocertain aspects, the repeated PBCH transmission may be triggered byreception of a bundled RACH transmission from a UE.

According to certain aspects, the eNB may signal rate matchinginformation for the repeated PBCH transmission via at least one of aSIB, RRC signaling, new PBCH rate matching information, or reuse ofquasi-collocation signaling.

FIG. 8 illustrates example operations 800 for wireless communications,in accordance with certain aspects of the present disclosure. Theoperations 800 may be performed, for example, by a UE (e.g., UE 120).The operations 800 may begin, at 802, by receiving (e.g., via a SIB, RRCsignaling, new PBCH rate-matching information, or reuse ofquasi-collocation signaling) rate matching information for a repeatedPBCH transmission in a radio frame. According to certain aspects, therepeated PBCH transmission may be repeated in at least one of a samesubframe or in different subframes of the radio frame.

At 804, the UE may process downlink transmissions in the radio frame,based on the rate matching information.

FIG. 9 illustrates example operations 900 for wireless communications,in accordance with certain aspects of the present disclosure. Theoperations may be performed, for example, by a base station (e.g., eNB110). The operations 900 may begin, at 902, by receiving a bundled RACHtransmission from a UE.

At 904, the base station may trigger bundled transmission of broadcastinformation (e.g., SIB, subset of available SIBs, PBCH, etc., orcombinations thereof) in response to receiving the bundled RACHtransmission.

According to certain aspects, the base station may transmit a bundledtransmission of a SIB that indicates a bundled PRACH configuration priorto detecting the bundled RACH.

FIG. 10 illustrates example operations 1000 for wireless communications,in accordance with certain aspects of the present disclosure. Theoperations 1000 may be performed, for example, by a UE (e.g., UE 120).The operations 1000 may begin, at 1002, by receiving a bundledtransmission of a SIB that indicates a bundled PRACH configuration.

At 1004, the UE may perform a bundled RACH transmission in accordancewith the PRACH configuration in order to trigger bundled transmission ofbroadcast information (e.g., a SIB, a subset of available SIBs, PBCH,etc., or combinations thereof).

According to certain aspects, the above techniques and apparatus may beapplied to machine type communications (MTC). According to certainaspects, the above techniques and apparatus may be applied in LTEunlicensed spectrum (LTE-U). For example, where transmissions are overwide bandwidth, broadcast transmissions (e.g., PBCH or synchronizationsignals) may be repeated in the frequency domain (e.g., outside of thecenter 6 resource blocks (RBs)). According to certain aspects, the abovetechniques and apparatus may be applied in high dimension multiple-inputmultiple-output (MIMO). For example, where antenna arrays forbeamforming gains, may not be applicable for PBCH, instead PBCH may berepeated or boosted for gains. According to certain aspects, the abovetechniques and apparatus may be applied to minimum away. For example, at60 GHz, propagation loss may be large and thus link budget enhancementmay be desired. PBCH may be repeated or boosted as described above toachieve the link budget enhancements.

As used herein, the term “determining” encompasses a wide variety ofactions. For example, “determining” may include calculating, computing,processing, deriving, investigating, looking up (e.g., looking up in atable, a database or another data structure), ascertaining and the like.Also, “determining” may include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“determining” may include resolving, selecting, choosing, establishingand the like.

The various operations of methods described above may be performed byany suitable means capable of performing the corresponding functions.The means may include various hardware or software component(s) ormodule(s), including, but not limited to a circuit, an applicationspecific integrated circuit (ASIC), or processor. Software shall beconstrued broadly to mean instructions, instruction sets, code, codesegments, program code, programs, subprograms, software modules,applications, software applications, software packages, firmware,routines, subroutines, objects, executables, threads of execution,procedures, functions, etc., whether referred to as software, firmware,middleware, microcode, hardware description language, or otherwise.Generally, where there are operations illustrated in figures, thoseoperations may have corresponding counterpart means-plus-functioncomponents with similar numbering. For example, operations 502-1002illustrated in FIGS. 5-10, respectively, correspond to means 502A-1002Aillustrated in FIGS. 5A-10A, respectively.

For example, depending on the configuration, means for transmitting maycomprise a transmitter or antenna(s) 252 of the UE 120, or a transmitteror antenna(s) 234 of eNB 110. Means for receiving may comprise areceiver or antenna(s) 252 of the UE 120, or a receiver or antenna(s)234 of eNB 110. Means for determining may comprise a processing system,which may include one or more controllers/processors, such as any of thecontrollers/processors of the UE 120 and the eNB 110 illustrated in FIG.2.

According to certain aspects, such means may be implemented byprocessing systems configured to perform the corresponding functions byimplementing various algorithms (e.g., in hardware or by executingsoftware instructions). For example, algorithms include an algorithm forobtaining a first set of one or more power allocation parameters for usein transmitting a PDSCH and an algorithm for transmitting a differenttype downlink transmission, with transmit power boosted relative to aPDSCH transmission sent using the first set of power allocationparameters, based on a second set of one or more power allocationparameters. In aspects, algorithms include an algorithm for receiving aPDSCH transmission, an algorithm for receiving a different type downlinktransmission, with transmit power boosted relative to the PDSCHtransmission, an algorithm for receiving information regarding relativetransmit power of the PDSCH transmission relative to a common referencesignal (CRS) based on the transmit power of the different type downlinktransmission, and algorithm for processing the PDSCH transmission basedon the information. In aspects, algorithms include an algorithm fortransmitting a PBCH in at least one subframe of a radio frame and analgorithm for repeating transmission of the PBCH in at least one of: thesame subframe or in a different subframe of the radio frame. In aspects,algorithms include an algorithm for receiving rate matching informationfor a repeated PBCH transmission in a radio frame and an algorithm forprocessing downlink transmissions in the radio frame, based on the ratematching information. In aspects, algorithms include an algorithm forreceiving a bundled RACH transmission from a UE and an algorithm fortriggering bundled transmission of broadcast information, in response toreceiving the bundled RACH transmission. In aspects, algorithms includean algorithm for receiving a bundled transmission of a SIB thatindicates a bundled PRACH configuration and an algorithm for performinga bundled RACH transmission in accordance with the PRACH configurationin order to trigger bundled transmission of broadcast information.

The various algorithms may implemented by a computer-readable medium,e.g., a non-transitory computer-readable medium. The computer-readablemedium may have computer executable instructions (e.g., code) storedthereon. For example, the instructions may be executed by a processor orprocessing system, such as any of the processors of the UE 120 or eNB110 illustrated in FIG. 2, and stored in a memory, such as memory 282 ofthe UE 120 or memory 242 of eNB 110. For example, the computer-readablemedium may have computer executable instructions stored thereon forobtaining a first set of one or more power allocation parameters for usein transmitting a PDSCH and instructions for transmitting a differenttype downlink transmission, with transmit power boosted relative to aPDSCH transmission sent using the first set of power allocationparameters, based on a second set of one or more power allocationparameters. In aspects, the computer-readable medium may have computerexecutable instructions stored thereon for receiving a PDSCHtransmission, instructions for receiving a different type downlinktransmission, with transmit power boosted relative to the PDSCHtransmission, instructions for receiving information regarding relativetransmit power of the PDSCH transmission relative to a common referencesignal (CRS) based on the transmit power of the different type downlinktransmission, and instructions for processing the PDSCH transmissionbased on the information. In aspects, the computer-readable medium mayhave computer executable instructions stored thereon for transmitting aPBCH in at least one subframe of a radio frame and instructions forrepeating transmission of the PBCH in at least one of: the same subframeor in a different subframe of the radio frame. In aspects, thecomputer-readable medium may have computer executable instructionsstored thereon for receiving rate matching information for a repeatedPBCH transmission in a radio frame and instructions for processingdownlink transmissions in the radio frame, based on the rate matchinginformation. In aspects, the computer-readable medium may have computerexecutable instructions stored thereon for receiving a bundled RACHtransmission from a UE and instructions for triggering bundledtransmission of broadcast information, in response to receiving thebundled RACH transmission. In aspects, the computer-readable medium mayhave computer executable instructions stored thereon for receiving abundled transmission of a SIB that indicates a bundled PRACHconfiguration and instructions for performing a bundled RACHtransmission in accordance with the PRACH configuration in order totrigger bundled transmission of broadcast information

The term “or” is intended to mean an inclusive “or” rather than anexclusive “or.” That is, unless specified otherwise, or clear from thecontext, the phrase “X employs A or B” is intended to mean any of thenatural inclusive permutations. That is, the phrase “X employs A or B”is satisfied by any of the following instances: X employs A; X employsB; or X employs both A and B. In addition, the articles “a” and “an” asused in this application and the appended claims should generally beconstrued to mean “one or more” unless specified otherwise or clear fromthe context to be directed to a singular form. A phrase referring to “atleast one of” a list of items refers to any combination of those items,including single members and duplicate members. As an example, “at leastone of: a, b, or c” is intended to cover, for example: a, b, c, a-b,a-c, b-c, a-b-c, aa, a-bb, a-b-cc, and etc.

The steps of a method or algorithm described in connection with thedisclosure herein may be embodied directly in hardware, in a softwaremodule executed by a processor, or in a combination of the two. Asoftware module may reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM or any other form of storage medium known in the art. Anexemplary storage medium is coupled to the processor such that theprocessor can read information from, or write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor. The processor and the storage medium may reside in anASIC. The ASIC may reside in a user terminal. In the alternative, theprocessor and the storage medium may reside as discrete components in auser terminal Generally, where there are operations illustrated inFigures, those operations have corresponding counterpartmeans-plus-function components with similar numbering.

In one or more exemplary designs, the functions described may beimplemented in hardware, software, or combinations thereof. Ifimplemented in software, the functions may be stored on or transmittedover as one or more instructions or code on a computer-readable medium.Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage media may be anyavailable media that can be accessed by a general purpose or specialpurpose computer. By way of example, and not limitation, suchcomputer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or otheroptical disk storage, magnetic disk storage or other magnetic storagedevices, or any other medium that can be used to carry or store desiredprogram code means in the form of instructions or data structures andthat can be accessed by a general-purpose or special-purpose computer,or a general-purpose or special-purpose processor. Also, any connectionis properly termed a computer-readable medium. For example, if thesoftware is transmitted from a website, server, or other remote sourceusing a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave, then the coaxial cable, fiber optic cable, twisted pair,DSL, or wireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and Blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Combinations of the above should also be included within the scope ofcomputer-readable media.

The previous description of the disclosure is provided to enable anyperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Thus, the disclosure is not intended to be limited tothe examples and designs described herein, but is to be accorded thewidest scope consistent with the principles and novel features disclosedherein.

What is claimed is:
 1. A method for wireless communications by a basestation (BS), comprising: transmitting a bundled simplified systeminformation block (SIB), to a user equipment (UE), that indicates abundled physical random access channel (PRACH) configuration; receiving,in accordance with the bundled PRACH configuration, a bundled RACHtransmission from the UE indicating a request for bundled broadcastinformation; and triggering a transmission of bundled broadcastinformation in response to the request indicated by the bundled RACHtransmission.
 2. The method of claim 1, wherein the transmission of thebundled broadcast information comprises transmission of bundled SIB2 andabove in response to the request indicated by the bundled RACHtransmission.
 3. The method of claim 2, wherein the transmission of thebundled broadcast information further comprises transmission of abundled physical broadcast channel (PBCH) in response to the requestindicated by the bundled RACH transmission.
 4. The method of claim 2,wherein the transmission of the bundled broadcast information furthercomprises transmission of a bundled SIB1 in response to the requestindicated by the bundled RACH transmission.
 5. The method of claim 1,wherein triggering the transmission of the bundled broadcastinformation, in response to the request indicated by the bundled RACHtransmission, comprises: opportunistically triggering the transmissionof the bundled broadcast information based on the receiving of thebundled RACH transmission.
 6. An apparatus for wireless communications,comprising: at least one processor; and memory coupled with the at leastone processor, the memory comprising code executable by the at least oneprocessor to cause the apparatus to: transmit a bundled simplifiedsystem information block (SIB), to a user equipment (UE), that indicatesa bundled physical random access channel (PRACH) configuration; receive,in accordance with the bundled PRACH configuration, a bundled RACHtransmission from the UE indicating a request for bundled broadcastinformation; and trigger a transmission of bundled broadcast informationin response to the request indicated by the bundled RACH transmission.7. The apparatus of claim 6, wherein the transmission of the bundledbroadcast information comprises transmission of bundled SIB2 and abovein response to the request indicated by the bundled RACH transmission.8. The apparatus of claim 7, wherein the transmission of the bundledbroadcast information further comprises transmission of a bundledphysical broadcast channel (PBCH) in response to the request indicatedby the bundled RACH transmission.
 9. The apparatus of claim 7, whereinthe transmission of the bundled broadcast information further comprisestransmission of a bundled SIB1 in response to the request indicated bythe bundled RACH transmission.
 10. The apparatus of claim 6, wherein thecode executable by the at least one processor to cause the apparatus totrigger the transmission of the bundled broadcast information, inresponse to the request indicated by the bundled RACH transmission,comprises: code executable by the at least one processor to cause theapparatus to opportunistically trigger the transmission of the bundledbroadcast information based on the receiving of the bundled RACHtransmission.
 11. A method for wireless communications by a userequipment (UE), comprising: receiving a bundled simplified systeminformation block (SIB) or a SIB1 transmission that indicates a bundledphysical random access channel (PRACH) configuration; performing abundled RACH transmission in accordance with the bundled PRACHconfiguration, the bundled RACH transmission indicating a request forbundled broadcast information; and receiving a transmission of bundledbroadcast information in response to the request for bundled broadcastinformation indicated by the bundled RACH transmission.
 12. The methodof claim 11, wherein the transmission of the bundled broadcastinformation comprises transmission of bundled SIB2 and above in responseto the request indicated by the bundled RACH transmission.
 13. Themethod of claim 12, wherein the transmission of the bundled broadcastinformation further comprises transmission of a bundled physicalbroadcast channel (PBCH) in response to the request indicated by thebundled RACH transmission.
 14. The method of claim 11, whereinindicating the request for the bundled broadcast information, comprises:opportunistically triggering the transmission of the bundled broadcastinformation based on the receiving of the bundled RACH transmission. 15.An apparatus for wireless communications by a user equipment (UE),comprising: at least one processor; and memory coupled with the at leastone processor, the memory comprising code executable by the at least oneprocessor to cause the apparatus to: receive a bundled simplified systeminformation block (SIB) transmission that indicates a bundled physicalrandom access channel (PRACH) configuration; perform a bundled RACHtransmission in accordance with the bundled PRACH configuration, thebundled RACH transmission indicating a request for bundled broadcastinformation; and receive a transmission of bundled broadcast informationin response to the request for bundled broadcast information indicatedby the bundled RACH transmission.
 16. The apparatus of claim 15, whereinthe transmission of the bundled broadcast information comprisestransmission of bundled SIB2 and above in response to the requestindicated by the bundled RACH transmission.
 17. The apparatus of claim16, wherein the transmission of the bundled broadcast informationfurther comprises transmission of a bundled physical broadcast channel(PBCH) in response to the request indicated by the bundled RACHtransmission.
 18. The apparatus of claim 15, wherein the code executableby the at least one processor to cause the apparatus to indicate therequest for the bundled broadcast information comprises: code executableby the at least one processor to cause the apparatus toopportunistically trigger the transmission of the bundled broadcastinformation based on the receiving of the bundled RACH transmission. 19.An apparatus for wireless communications, comprising: means fortransmitting a bundled simplified system information block (SIB)transmission, to a user equipment (UE), that indicates a bundledphysical random access channel (PRACH) configuration; means forreceiving, in accordance with the bundled PRACH configuration, a bundledRACH transmission from the UE indicating a request for bundled broadcastinformation; and means for triggering a transmission of bundledbroadcast information in response to the request indicated by thebundled RACH transmission.
 20. A non-transitory computer readable mediumstoring computer executable code thereon for wireless communications,comprising: code for transmitting a bundled simplified systeminformation block (SIB) transmission, to a user equipment (UE), thatindicates a bundled physical random access channel (PRACH)configuration; code for receiving, in accordance with the bundled PRACHconfiguration, a bundled RACH transmission from the UE indicating arequest for bundled broadcast information; and code for triggering atransmission of bundled broadcast information in response to the requestindicated by the bundled RACH transmission.
 21. An apparatus forwireless communications, comprising: means for receiving a bundledsimplified system information block (SIB) transmission that indicates abundled physical random access channel (PRACH) configuration; means forperforming a bundled RACH transmission in accordance with the bundledPRACH configuration, the bundled RACH transmission indicating a requestfor bundled broadcast information; and means for receiving atransmission of bundled broadcast information in response to the requestfor bundled broadcast information indicated by the bundled RACHtransmission.
 22. A non-transitory computer readable medium storingcomputer executable code thereon for wireless communications,comprising: code for receiving a simplified system information block(SIB) transmission that indicates a bundled physical random accesschannel (PRACH) configuration; code for performing a bundled RACHtransmission in accordance with the bundled PRACH configuration, thebundled RACH transmission indicating a request for bundled broadcastinformation; and code for receiving a transmission of bundled broadcastinformation in response to the request for bundled broadcast informationindicated by the bundled RACH transmission.